Congenital Toxoplasmosis: Erythrocebus patas is the monkey most suitable for studies of acquired toxoplasmosis. They are readily infected by oral administration of toxoplasma cysts. The infection in this monkey closely resembles that in humans. The animals become ill for several days, then as antibody develops they gradually recover. A dosage that will infect the pregnant animal and not invariably result in abortion is being determined. Rubella Virus: Rubella virus produces congenital infection in the patas monkey. The virus was isolated from various fetal tissues 77 to 120 days after intra-amniotic inoculation into pregnant patas monkeys at 40 days gestation. This presents an opportunity to study the pathogenesis of this important human teratogen.